A tiger looks out from a cage at the Shanghai Zoo on Dec 17, 2013, as a man passes by.[Sun Zhan/ for China Daily]

According to the Shanghai Zoo, Zhou was attacked at about 10:30 am on Tuesday. The 57-year-old Shanghai native, a keeper for almost 30 years, was killed by the South China tiger, which was bred and born at the zoo and has given birth to several cubs.

Zhou's colleagues found him dead on the floor of the tiger's cage during lunchtime after realizing he had been missing all morning.

"Zhou might have forgotten to close the door after cleaning the tiger's cage," said a director at the zoo's breeding department named Tu.

Medical workers pronounced Zhou dead at the scene.

Zhou and another zookeeper had been taking care of the tiger for several years since it reached adulthood, Tu said. The tiger has lived its whole life in the zoo, Tu said.

The animal will not be killed or punished, zoo officials said, but will remain in its usual place.

This is the second time an animal has killed a keeper at the Shanghai Zoo. In 2010, a Bengal tiger killed its keeper and dragged the man's body around the cage as visitors looked on in horror.

Jiang Guangshun, a tiger expert at Northeast Forestry University, said animals in captivity try to hurt people only when they feel threatened or not at ease.

"In many cases of zoo animals hurting people, the keepers harmed thought they were too experienced or familiar with the animals to be harmed, and overlooked the rules," he said.